Field of the Invention
The present invention relates to a valve apparatus equipped with a diaphragm, which opens and closes a fluid passage that establishes communication between a first port and a second port and through which a fluid flows.
Description of the Related Art
Heretofore, a valve apparatus has widely been used equipped with a body, in which there is formed a fluid passage that establishes communication between a first port and a second port and through which a fluid flows, and a diaphragm that opens and closes the fluid passage by separating away from or being seated on a valve seat formed in the body. In this type of valve apparatus, for example, in the event that a corrosive fluid (such as ozone gas or ultrapure water) is utilized as the pressure fluid, the diaphragm and the body, respectively, are constituted from a fluorine resin that is resistant to corrosion.
Notwithstanding, in the event that the body and the diaphragm are each constituted from such a fluorine resin, which is a non-conductive material, static electricity is generated as a result of friction between the diaphragm and the valve seat, or by friction between the diaphragm and the pressure fluid. In addition, when static electricity is accumulated in the diaphragm, dielectric breakdown (spark discharge) occurs which may cause damage to the diaphragm.
Thus, valve apparatus have been proposed that include mechanisms for preventing dielectric breakdown of the diaphragm. For example, in Japanese Patent No. 4705490, a technical concept is disclosed in which, in a diaphragm valve equipped with a diaphragm retainer having a non-conductive first resilient member for holding an outer edge of the diaphragm, and a second resilient member that is attached via a conductive sheet to the underside of the first resilient member, static electricity generated in the vicinity of the diaphragm retainer is led out to a ground wire via the conductive sheet.
Further, for example, in Japanese Patent No. 4461087, a technical concept is disclosed in which an anti-corrosive conductive member is arranged in a through hole that penetrates to the side of a fluid passage in the vicinity (outer edge) of a membrane of the diaphragm, and an o-ring is provided to effect sealing between the conductive member and a wall surface that constitutes the through hole, wherein static electricity that is generated in the diaphragm is led out to a ground wire via the conductive member.
Furthermore, in Japanese Laid-Open Patent Publication No. 2010-121689, a technical concept is disclosed in which a spiral shaped conductive film is formed on a side of a diaphragm that does not come into contact with the pressure fluid, and static electricity that is generated in the diaphragm is led out to ground via the conductive film.